Thermal operations for oil recovery, such as steam assisted gravity drainage (SAGD) or cyclic steam stimulation (CSS), produce large quantities of low temperature waste heat. Steam assisted gravity draining may typically involve a high temperature high pressure fluid to be sent below ground to recover oil. When the fluid returns to the surface, some of the heat has dissipated, but there still remains a large amount of low temperature waste heat that is released to the environment without further utilization. Initial heating of fluid may be accomplished using natural gas, either purchased or derived from on-site sources.
Certain thermal operations, some of which involve water re-use, may have no immediate heat sink available for re-using heat generated in the operation. Thus, low grade waste heat generated by the operation is typically discharged to the atmosphere. For example, a conventional SAGD operation may produce in the order of 30 MW of waste heat when hot glycol (60-80° C.) produced in the operation is cooled to about 30° C. In current economic terms, this quantity of waste heat translates into approximately $5 million per year.
Bitumen mining operations, as may be found in the oil sands in Alberta, Canada, require large quantities of low grade heat. In a conventional mining operation located proximal to a river, a significant amount of heat is required to raise the initial river water temperature (starting at about 2-15° C.) by approximately 30-40° C. to reach the desired process temperature (about 35-45° C.).
It is, therefore, desirable to provide a method and a system capable of obtaining and recovering waste heat to be advantageously utilized as an energy saving measure.